In a general industrial machine field, although mechanical control elements are driven by an electric motor, recently, an electric drive device has been adopted in which an electronic controller formed of a semiconductor element and the like for controlling the rotation speed and the rotation torque of an electric motor is integrally incorporated into the electric motor. That is, a mechanically and electrically integrated electric drive device has been adopted.
As an example of the mechanically and electrically integrated electric drive device, for example, in an electric power steering device of an automobile, a rotation direction and rotation torque of a steering shaft which rotates when a driver operates a steering wheel are detected, and, based on this detection value, steering assist torque is generated by driving the electric motor such that the steering wheel rotates in the same direction as the rotation direction of the steering shaft. In addition, to control this electric motor, an electronic control unit (ECU) is provided to the power steering device.
In this electric power steering device, the electric motor is accommodated in a motor housing having a cylindrical part made of, for example, aluminum alloy, and the electronic control unit is accommodated in an ECU housing arranged on the opposite side to the output shaft in the axial direction of the motor housing. The electronic control unit accommodated in the ECU housing is provided with a power supply section, a power conversion circuit section having a power switching element such as MOSFET for driving and controlling the electric motor, and with a control circuit section for controlling the power switching element, and the output terminal of the power switching element and the input terminal of the electric motor are electrically connected to each other through a bus bar.
In addition, electric power is supplied to the electronic control section accommodated in the ECU housing from a power supply through a connector assembled body made of synthetic resin, and a detection signal of a driving condition is sent thereto from a detection sensor. The connector assembled body functions as a lid body, is connected to the electronic control section so as to close the opening part formed in the ECU housing, and is fixed to the outer surface of the ECU housing by a fixing bolt.
By the way, in this type of the electronic control section, the power switching element of the power conversion section for driving and controlling the electric motor is controlled by a control signal from the control circuit section, and a circuit board of the control circuit section and a circuit board of the power conversion circuit section are connected by a connection terminal assembled body.
This connection terminal assembled body is placed onto the circuit board of the power conversion circuit section and then is adhered onto and fixed to the circuit board with solder.
The soldering of this type of the connection terminal assembled body is generally performed by “reflowing process”. The “reflowing process” is a method in which paste-like solder that is called as cream solder is applied to a required place of a wiring pattern of the circuit board in advance, and the connection terminal assembled body is placed thereon and then the soldering is performed by directly heating the circuit board to melt the solder.
In addition, in general, placing stability of the connection terminal assembled body is poor. Therefore it is difficult to set the connection terminal assembled body into a self-standing state, and moreover, when the solder is melted in a soldering process, the connection terminal assembled body falls down. Therefore it is necessary to set the connection terminal assembled body into a self-standing state by using a special fixture, and productivity cannot be improved.
Here, as a method for smoothly performing the “reflowing process” by placing the connection terminal assembled body onto the circuit board by an automatic machine (chip mounter), for example, a method described in Japanese Patent Application Publication No. 2015-60958 (patent document 1) has been known. In the patent document 1, to automatically place the connection terminal assembled body onto the circuit board, the shape of the connection terminal assembled body is formed of a long plate-shaped placing section formed with a suction surface for pick up by an automatic machine and unit connection terminals for performing electrical connection between the circuit board and the circuit board connected to the placing section.
Here, the placing section also functions to set the connection terminal assembled body in a self-standing state, and when, after the connection terminal assembled body is placed in the self-standing state by being picked up by the automatic machine, the soldering by the “reflowing process” is completed, the part between the placing section and the unit connection terminals is cut such that the unit connection terminal remains on the circuit board. According to this configuration, by the placing section of the connection terminal assembled body, it becomes possible to perform the pick up by the automatic machine, and moreover, it is possible to place the connection terminal assembled body in the self-standing state, and thereby it becomes possible to solder the connection terminal assembled body onto the circuit board without using a special fixture.